'Riverdale' fans finally know what the parents' big secret is and there's a murder involved

"Riverdale" has been teasing a deadly secret between some of the parents, and the truth has finally been revealed.

On Wednesday's flashback episode of the hit CW show, Alice Cooper explains to Betty what happened one fateful night when the parents were juniors in high school. Little did they think their high school secret would come to haunt them as adults.

Here's everything we know about the secret.

The parents' pact is connected to "Gryphons and Gargoyles."

Hermione gathers the parents together. The CW

The second episode of season three ends with Hermione and Hiram Lodge, Tom Keller, Sierra McCoy, FP Jones, Fred Andrews, Penelope Blossom, and Alice seated in Hermione's mayoral office.

"We made a vow in high school," Hermione says. "Look, now that the scout is back, safe and sound, thank God, we can only assume that he'll start talking and that whatever he says might lead back to us, to the secret that we buried all those years ago."

Hermione then tells the parents about Dilton, who is dead, and Ben, who is in a coma, being found with blue lips. Because Jughead is the one who found the bodies, the parents know that they won't be able to sweep that detail under the rug.

"We made a pact to never revisit that night," Tom says. "Not to mention it, not to even think about it. My vote is we stick with that."

Hermione says they won't be able to do that if it's putting their children at risk.

Jughead and Betty learn that the blue lips are a consequence of a game called "Gryphons and Gargoyles." Jug decides to play the game with Ethel to gain access to the game's manual.

When FP discovers the manual, he and Alice freak out on Betty and Jughead.

"This game is pure evil," FP says before burning the manual in a fire.

Betty goes to Alice to find out what the parents know about the game, and Alice tells the whole story.

They kept a deadly secret from junior year.

FP, Penelope, and Fred playing the game in high school. The CW After ending up in detention together their junior year, FP, Alice, Fred, Penelope, Sierra, and Hermione find "G&G" in a teacher's desk. They start to play and quickly become addicted. They dress up, they follow quests, and they even sneak into the school after hours to continue their game.

One night, as they are prancing around the halls in costume, they hear noises and run into Hiram, Marty Mantle, and Daryl Doiley also dressed up and on a quest for "G&G." The two groups unite for an even bigger game.

They all receive invites to a special night to "ascend to the next level of the game." Daryl and Penelope each think each other set the party up, but neither of them did. At the ascension party, Hiram hands everyone a drug called Fizzle Rocks, and everyone except for Alice takes it. The teens embark on a crazed night and run around the school.

Alice runs into the bathroom to throw up, but when she emerges, she finds the bathroom covered in symbols and the words "flip for your fate." On a sink sits two chalices and a coin. She runs out of the bathroom before running into the Gargoyle King.

As she is running out of the school, she sees Principal Featherhead walk in. The next morning, Featherhead is missing. After days of searching, they find his decomposing body in a school closet with symbols carved on the door and a blue tint to his lips.

Alice gathers the group together to ask what happened.

"There was blue liquid in the chalices when I saw them," she says. "Featherhead's corpse had blue lips, and the police said he had poison in his system. What did you guys do to him?"

Everyone says they didn't see him or the Gargoyle King at the school. Alice wants to go to the cops, but the group doesn't want to. Penelope tells them that neither she nor Daryl set the quest up.

"The chalices were just sitting there," Alice says. "Anyone of us could have drank from them, so whoever invited us to the ascension party was trying to kill one or more us."

Despite Alice's protests, everyone decides to destroy the game by burning the manuals and hiding the pieces. They make a pact to hide the secret and everyone split off from each other.

What this means for the kids in Riverdale.

Betty finds Jughead playing the game. The CW

Betty asks her mom who could have done it, and Alice says they thought it had to have been one of the group members.

"One of us was a murderer," she says. "Whoever poisoned those cups meant for one of us to drink it at the end of the quest."

Alice begs Betty not to play the game, and she promises she won't.

Betty goes to school to check on some of the facts Alice shared with her, and she finds two G&G chalices in the trophy case at school. She goes to tell Jughead what she learns, but finds him at Dilton's bunker playing the game with Toni, Cheryl, Sweet Pea, and Fangs.

"It's all making sense," Jughead tells her. "All of this is becoming clear...I'm a level three, and it's only a matter of time until I ascend, and I get to meet him."

Now that Betty knows the truth and her friends are in too deep, it's up to her to figure out a way to stop it.